package pers.gxm.interpreter;

import java.util.StringTokenizer;

public class Context {
    private StringTokenizer tokenizer;
    private String currentToken;
    public Context(String text){
        tokenizer = new StringTokenizer(text);
        nextToken();
    }

    public String nextToken(){
        if(tokenizer.hasMoreTokens()){
            currentToken = tokenizer.nextToken();
        }else{
            currentToken = null;
        }
        return currentToken;
    }

    public String currentToken(){
        return currentToken;
    }

    public void skipToken(String token) throws ParseException {
        if(!token.equals(currentToken)){
            throw new ParseException("Warning: " + token + "is expected, but" + currentToken + "is found.");
        }
        nextToken();
    }

    public int currentNumber() throws ParseException {
        int number = 0;
        try{
            number = Integer.parseInt(currentToken);
        }catch(NumberFormatException e){
            throw new ParseException("Warning: " + e);
        }
        return number;
    }
}
